The meniscus is a C-shaped piece of fibrocartilage which is located at the peripheral aspect of the joint (e.g., the knee) between the condyles of the femur and the tibia on the lateral and medial sides of the knee. The central ⅔rds of the meniscus has a limited blood supply while the peripheral ⅓rd typically has an excellent blood supply. Acute traumatic events commonly cause meniscus tears in younger patients while degenerative tears are common in older patients as the menisci become increasingly brittle with age. Typically, when the meniscus is damaged, a torn piece may move in an abnormal fashion inside the joint, which may lead to pain and loss of function of the joint. Early arthritis can also occur due to these tears as abnormal mechanical movement of torn meniscal tissue and the loss of the shock absorbing properties of the meniscus lead to destruction of the surrounding articular cartilage. Occasionally, it is possible to repair a torn meniscus. While this may be done arthroscopically, surgical repair using a suture has proven difficult because of the hard-to-reach nature of the region and the difficulty in placing sutures in a way that compresses and secures the torn surfaces.
Arthroscopy typically involves inserting a fiberoptic telescope that is about the size of a pencil into the joint through an incision that is approximately ⅛ inch long. Fluid may then be inserted into the joint to distend the joint and to allow for the visualization of the structures within that joint. Then, using miniature instruments which may be as small as 1/10 of an inch, the structures are examined and the surgery is performed.
FIGS. 1A-2 illustrate the anatomy of the meniscus in the context of a knee joint. As shown in FIG. 2 the capsule region (the outer edge region of the meniscus) is vascularized. Blood enters the meniscus from the menisculocapsular region 211 lateral to the meniscus. A typical meniscus has a flattened (“bottom”) and a concave top, and the outer cross-sectional shape is somewhat triangular. The outer edge of the meniscus transitions into the capsule. FIG. 3 illustrates the various fibers forming a meniscus. As illustrated in FIG. 3, there are circumferential fibers extending along the curved length of the meniscus, as well as radial fibers, and more randomly distributed mesh network fibers. Because of the relative orientations and structures of these fibers, and the predominance of circumferential fibers, it may be beneficial to repair the meniscus by suturing radially (vertically) rather than longitudinally or horizontally, depending on the type of repair being performed.
For example, FIGS. 4A-4E illustrate various tear patterns or injuries to a meniscus. Tears may be vertical/longitudinal (FIG. 4A), Oblique (FIG. 4B), Degenerative (FIG. 4C), including radially degenerative, Transverse or radial (FIG. 4D) and Horizontal (FIG. 4E). Most prior art devices for suturing or repairing the meniscus are only capable of reliably repairing vertical/longitudinal tears. Such devices are not typically recommended for repair of radial tears, particularly not arthroscopically/minimally invasively. FIGS. 5A-5C illustrate sutures placed with prior art devices to repair (via suturing) a torn meniscus (showing a longitudinal tear). FIG. 5A illustrates the results of a repair by a Smith & Nephew “Fast-Fix” device (comparable to a repair by a Biomet MaxFire device). FIG. 5B illustrates a Cayenne “CrossFix” device, and FIG. 5C illustrates a repair using an Arthrex meniscal “Viper” device.
In FIGS. 5A-5C the devices affecting these repairs require projection through the meniscus and substantially into the capsule region outside of the meniscus, which could potentially damage the nearby major nerves and large blood vessels. Further, the prior art devices, such as those placing the sutures illustrated in FIG. 5A-5C, typically place horizontal mattress suture patterns rather than vertical mattress suture patterns because vertical patterns are considerably more difficult (if not impossible) for surgeons to place when using these devices. Vertical mattress patterns would have improved pull through strength because of the aforementioned predominance of circumferential collagen fibers found within the meniscus structure. See, e.g., Boenisch, U. W., et al, “Pull-out strength and stiffness of meniscal repair using absorbable arrows or Ti-Cron vertical and horizontal loop sutures,” Am J Sports Med. 1999 September-October; 27(5):626-31. Additionally, the devices forming the suture patterns illustrated in FIG. 5A-5C are only capable of point fixation; that is they cannot compress the tears uniformly across the torn surface. Finally, such prior art devices are designed for repairing peripheral vertical meniscus tears (torn from the superior surface to the inferior surface in line with the C-shape of the meniscus) and are incapable of repairing commonly encountered radial meniscus tears.
Thus, there is a need for methods, devices and systems for repairing a torn meniscus that allow repair of the meniscus in a manner that decreases patient discomfort and enhances the rate of recovery. In particular, it would be beneficial to provide methods, devices and systems capable of repairing both radial and longitudinal tears without risking additional damage to the meniscus or the vascular systems feeding the meniscus. In addition, it would be highly beneficial to provide methods and devices allowing a physician to minimally invasively suture the meniscus in a vertical loop. The methods, devices and systems described herein may address this need.